Supersonic heterodyne receiver



May 5, i936.

C. P. OSBORNE SUPERSQNIC HETERODYNE RECEIVER F11ed Feb. 12, 1934 2.sneets-shet 1 www# INVENTOR CHARLES OSBORNE May 5, g. C P, QSBQRNE Zgg?sUPERsoNIc HETERODYNE RECEIVER Filed Feb. l2, 1954 2 Sheets-Sheet 2INVENTOR ATTORNEY CHARLES P. OSBORNE i* l'ie'terodyne receivers forvwireless-or like reception.' In'recei'vers 'offthisrkindI anfincomingcarrier,"

"modulated iwithA Aafsignail,"and of a frequency-' "whichwillhereina'fter b'e referred to asthe :signal frequency, is causedtobeat with-a locally'gen-"- `erateld oscillatipnithe'frequency of whichwill bef1 calledthe oscillator'frequency, and the result- Patented May5, 1936 STATES Pirl-#EN'rful foFFflcE 2,039,657 "sUPRs'oNIcl"HETERODYNE" vRECEIVER 7 Charles'fPercy Gsbcrne,EHillin'g'don,"England;`as

. 'sig'nor tol Electric and Musical Industries'Lim- 'ited,y Hayes,England, a. company of Great Britain l'^'A''prilicatiorrFebruary 12;;1934;?Seri'al Nef-'710,804

l" In Great BritaiFebllaiy- 13,1933

comms. (ci. y25W-,20)

'The*present*"inventionrelatestokv'supersonicf-F""generating*oscillations of-*the""`oscil1ator ire-"que'nc'y ffolareffed to lrs't detector v4 for beats aiedet'eotedandfedto the input ofiv an intermediate frequency amplieri'tunedto the beator'Aintermediate `frequency. The `output w fa;rv 'further2 amplirflprovided? vfor amplifying the modulation frequencies. v A

*The -wliole ora part of the-output voltage of from this* amplifierisrectified in :a second de-f'jfthe intermediate frequency amplifier 5-isapplied tector tcryield4` the signals.

to variations injthe' oscillator frequency. Quite f betweentl'ie-controlgrid 8 and the cathode 9 of 'Difficulty isexperiencedparticularly withrean' auxiliary'therniionicfvalv I0; -that 'is to say, ceivers suitable"for ultra-shortv Wave working in foscillatioris of?aifre'qui-iificyv f1are? produced in the which-the' signal frequencies are very high; duecontrol g'rid"circuit of this Valve. The control gr'id8fisgivenasuitablenegative biasing potenrise to af'ver'y'largepercentage change in the 'jintermediate frequency. Another difliculty'met --with isthe extreme sharpness Withwhich cir-4 cuits tune tothesehigh frequencies.

:a small change in the oscillator frequency gives,

One Way in-which thesedifliculties have been 'idealt'with hithertoI isbygiving the intermediate'- 'ffr'equency amplifier 'a band-passcharacteristic- =-'which is-muchwider than would normally bear' desired.For example, when receiving a signal: l.

"-" frequency of 90 megacycles/sec." modulated with frequencies upto`5,'000 cycles/sec., the band width-y f fmay beinade lokilocycles/sec.thus permitting a drift of 90 kilocycles/sec. which is'still only onepart in a'thousand andrmaywell happen in It is an-object ofthe presentinvention to provide means for improving the constancy of the oscillatorfrequency. c vAccording to the present invention, a super-1y "sonicheterodyne receiverlis provided' with means fr generating a harmonic ofthe intermediate` frequency and'means for utilizing this harmonick Y toAreduce variations in'` the loscillator frequencyf' AThe inventionv willbel described by way of example `With"reference to 'the'21.c'coinpanying'v drawings', whereinvFig. 1' shows one embodiment of"the'f vinvention;"Figa 2 showsanotherform' yvheterodyne receiverAcomprises a grounded ante-n-4 na'circuit l feeding anamplilier 2; tunedto the '-55i`a'inplier 2y and from"the'rmionic means 3' fori vReferringto-'Fi`g."1 of 'thedrawings a Superfy signal vfrequency (fs). "I'heoutputsffrornr thel tial'relatively'tothe cathode 9 by means of abattery- I I,"forf"example. Between "the screening gridfIZ'aiidvcathodeBlof thev'alve lll is' arranged apa'rallel'resonant circuit`l3'tuned toa harmonic of f1; namelyl a"frequency mf1,"wher'e m is aninteger.ff"-The1 screening f' grid I 2 is maintained.

at :va-suitable' positive potential withrespect to f they cathode 9; Theanode I4 of the valve is con- 'l nected 'to' itsl cathode through aparallel resonant circuit I5''tuned tothe` oscillator frequency fo,anda-source "|36 of anode current in series. The

*frequency ifo is made Aequal' to a harmonic of f1 so`fthat'^f=Kf1'whereK is an integer, and 'vKnmj-'where n vi's aninteger.' The valve l0'-thu'sgenerates "arid selects the mth harmonic of fi" in' itsscreen-grid-lcathode circuit and the "-'nth harmonic of this mthharmonic of f1 in its anode-cathode circuit; the overall result being algeneration in the anodeecathode circuit of the `-Kth `harmonicoffthefrequency applied to the control grid circuit. i-Theresonantcircuit l is -coupled in: the arrangement illustrated to the oscillatorycircuit Il ofthe oscillator 3, and the arrangement is suchthat Vthecoupling between 4the anode-cathodelcircuit of the-auxiliary valve "poseifo" changes to (l-l-mfo Iiilhere'a, is Va posi- "tive 'oi' negativefraction, vthen" the change in fn is l lpztjnfthecha'nge in f1 is '-wfu'and the change in jthereof;"'Fig. S'sliows still anothervmodification*`vv l valve islKafo.' 'Thus echange in frequency of'thefcontroll frequencydelivered by the auxiliary theffoscillatoryoffiii-ajn is `acc-omplar'iied`I by a 'chan' v ,off-#Kafq inithefcontrol frequency; that is ftof'say the ontrolfffrequency changes Ktimes a'senuch in'iftheopposite-senseg-and by suitable cycles/sec.

coupling can therefore be made to prevent changes in oscillatorfrequency.

In one example f0=36 and f1=6, both in mega- In order to obtain acontrol frequency from ,f1 it is therefore necessary to select the 6thharmonic (K=6) and this may be done, for example, by generatingandselecting the 3rd harmonic of f1, that is 18 megacycles, in the screengrid circuit of the auxiliary valve (171:3) and byV generating thesecond harmonic of18 megacycles, that is 36 megacycles, in the anodecircuit (11.:2) In this case any change in oscillator frequency isaccompanied by a change in the control frequency of six times the amountin the `opposite sense. Y

In a modified receiver according to the invention, as shown in Fig. V2,the functions of the oscillator valve and the auxiliaryrvalve areperformed by a single valve 20, which may be a so-called heptode inwhich five grid electrodes are arranged between the cathode and ananode.l

In such an arrangement, the second grid 2|, if

connected to the cathode through a resonant circuit 22 tuned to theoscillator frequency, in series with a source of anode current 23 andthe circuit ofthe first grid 24 includes av coupling Y coil 25, thefirst and second gridsco-operating with the cathode to generate Vtheoscillator frequency.

The third and fifth grids are connected together, and the anode 26 isconnected to the cathode through a circuit 21 coupled to that in Y thesecond grid circuit and tuned to the same frequency, that is, theoscillator frequency, .and the source of anode current in series. YThewhole or a part of the outputvvoltage of the intermediate frequencyamplifier is applied between the fourth grid 28 and the cathode, and thethird and fifth grids are connecte-d through a circuit 29 tuned to amultiple of the intermediate frequency and a` sub-multiple of theoscillator freoscillator frequency should be as weak as pos- Y .adynatron oscillator.

In an alternative arrangement shown. in Fig. 3

in which a single valve serves both as the oscillator valve and as theauXiliary'v-alve, a thermionic tetrode 30 is so connected as to functionas The potentials applied, relative Vto the cathode, to the anode 3| andscreening grid 32 are so adjusted that the anodecathode path of thevalve has a negative resistance characteristic. oscillations at theintermediate frequency are fed to the control grid circuit, andthescreening grid circuit comprises a resonant circuit 33 tuned to aharmonic of this frequency. The anode circuit comprises a circuit 34tuned to the oscillator frequency, which is arranged to be a harmonic ofthe frequency of the oscillations generated in rthe screening gridcircuit, and the oscillations generated in th anode circuit are fed tothe first detector.

The resonant circuits in which the harmonics of the intermediatefrequency are generated should, in all cases, preferably be of lowdecre-V ment in order that substantially only the desired harmonicfrequencies are generated. By making these circuits sharply tuned, thetendency for the oscillator frequency to be affected by harmonics offrequencies occurring in the intermediate frequency side bands isprevented.

The invention is of particular value in the case of apparatus adaptedfor the reception of signals representing a picture or scene and a soundaccompaniment, in which the two sets of signals are transmitted atdifferent carrier frequencies, and in which a single oscillator is usedto provide both intermediate frequencies.

Where it is desired to makeV the receiver tunable over a range of signalfrequencies, means may be provided whereby the circuits tuning to thefrequencies fs and fo have their resonant frequencies changedsimultaneously in the proper proportion by theactuation of a singlecontrol member 35. Thusthe circuit tuning 'to .fs is made to be resonantalways at a frequency (1+ K) times the frequency to which theintermediate frequency amplifier is tuned and, of course, the oscillatorfrequency is maintained equal to Kfi.

I claim. 1. The method of maintaining a receiver of the heterodynedltype in tune to the received wave which includes thel steps of, beatingsaid wave Y with local oscillations to produce oscillations of adifference frequency, multiplying said oscillations Yof a differencefrequency and entraining said 1o"- cal oscillations with said multipliedoscillations.

2. The method of'maintaining a receiver o f the heterodyned type in tuneto the received wave, which includes the steps of, beating said receivedWave with local oscillations to produce oscilla'- tions of anintermediate frequency, increasing the frequency of said intermediatefrequency oscillations to a value substantially equal to the fren quencyof the local oscillations and superimposing said oscillations ofincreased frequency on said local oscillations. Y

3. The method of reducing the amount of shift produced in theintermediate frequency of a receiver of the heterodyned type when thereceived wave shifts in frequency, which includes the steps of, beatingsaid received Wave with local oscillations to produce oscillations of anintermediate frequency, multiplying the frequency of said intermediatefrequency oscillations to a value substantially equal to the frequencyof the local oscillations and entraining said local oscillations withsaid oscillations of multiplied frequency.

4. In a heterodyned receiver, the combination of a first detectorresponsive to signal waves to be demodulated, an oscillator coupled tosaid first detector, a utilization circuit coupled to the output circuitof said first detector and a frequency multiplier having its inputcircuit coupled to the to a frequency bearing a predetermined harmonicrelation to the oscillator frequency and the rst detector output circuitfrequency, and said multiplier input circuit being connected between thegrid and cathode.

6. In a. receiver as dened in claim 4, said multiplier including ascreen grid tube, and a. resonant network connected between the screengrid and output circuit of the multiplier tube which is tuned to a.frequency bearing a. predetermined harmonic relation to the frequenciesof the oscillator output energy and the rst detector output 5 energy.

CHARLES PERCY OSBORNE.

